Previous methods of extracting lithium values from brines which contain lithium are disclosed in the following U.S. Pat. Nos. 4,116,856; 4,116,858; 4,159,311; 4,221,767; 4,291,001; 4,347,327; 4,348,295; 4,348,296; 4,348,297; 4,376,100; 4,381,349; 4,430,311; 4,461,714; 4,472,362; and 4,477,367. These patents pertain, in various ways, to creating lithium aluminates within the interstices or pores of ion exchange resins, or on other substrates, porous and non-porous. Microcrystalline lithium aluminates formed within ion exchange resins are useful in selectively removing lithium values from Li-containing brines. Over the years, it has been found that ion exchange resin compositions were often fouled by substances in the brine, such as hydrocarbon contaminants, that rendered the ion exchange resin incapable of rejuvenation requiring manufacture of resin.
In Lithium--Current Applications in Science, Medicine and Technology, R. O. Bach Editor, published by John Wiley and Sons, 1985, there is a paper on pp. 29-34, by W. C. Bauman, J. L. Burba, and J. M. Lee, titled "Structure and Operation of Dow's New Lithium-Selective Ion-Exchange Resin" containing background information of some relevance to the subject matter of this present disclosure.
The present invention offers improvements in costs and availability of materials for recovering lithium values from brines. The hydrated alumina pellets of the present invention are so inexpensive, compared with ion exchange resins, that it is more cost effective to discard spent hydrated alumina than to rejuvenate it. Also, the preparation of the lithium-capturing pellets of the present invention is relatively simple and easily managed in situ in a vessel in which it is to be used, though it can be prepared in one vessel and then transferred to another vessel for use. A more concentrated and more pure LiX product can be prepared, as compared to the known use of ion exchange resins.